Furnaces are routinely used in the production and treatment of metals to anneal, harden, age, pre-age, treat, or soften metals for further processing. Some furnaces may be used to treat metal sheet or plate in a continuous manner as the material is drawn through the length of the furnace.
Today, increasing demand for metal sheet and plate, combined with a drive for higher material quality and more complex treatment processes, has led to an increase in the size of treatment furnaces. Furnaces have been developed with increasing length and multiple heating zones of differing temperatures for more complex heating processes, higher quality product, and faster processing speeds.
However, longer furnaces are expensive and consume valuable space in metal processing plants. Longer furnaces also add additional stresses to the metal sheet or plate as it is drawn through the length of the furnace. The additional stresses due to a longer furnace can cause instability of the metal sheet or plate and can lead to tearing or material defects. Longer furnaces also have significant thermal inertia and require relatively long periods of time to raise or lower the temperature of their treatment zones. As a result, they may be slow to respond to changes in material composition, material thickness, line speed, or material treatment process. The slow response of traditional metal treatment furnaces requires either lengthy delays during processing or the use of transition material that must then be scrapped as a waste product.